Laboratory investigation of the impact of water-cement ratio on the mechanical properties and durability of roller-compacted concrete mixtures containing polypropylene fibers

Due to the development of the design and implementation of roller-compacted concrete pavements (RCCPs) in recent years, the issue of roller-compacted concrete (RCC)'s strength has been of special significance. Despite advancements in RCCP design, the optimal water-cement ratio (w/c) for maximizing strength and durability, particularly with fiber reinforcement, remains underexplored. This study addresses a critical gap in the understanding of RCCPs by examining the influence of w/c on the mechanical properties and durability of RCC mixtures enhanced with polypropylene (PP) fibers. In this regard, compressive strength, flexural strength, splitting tensile strength, and durability tests were performed on the samples. The results showed that the addition of PP fibers to RCC mixtures improved the compressive, flexural and splitting tensile strength and durability of samples significantly. It was indicated that w/c of 0.40 and 0.5% PP fiber content resulted in the highest compressive, flexural, splitting tensile strength of 86, 9.49 and 6.94 MPa, as well as the lowest water absorption value of 2.99% compared to the control sample, where the consumption of cement decreased by about 12%. Also, there was a good relationship between the dry density of the samples and their water absorption percentage. These findings suggest that fine-tuning w/c in PP fiber-reinforced RCC can lead to more durable and sustainable pavements, marking a significant step forward in RCCP design.